Stem for electric lamps and similar devices



Jan. 10, 1939. J. FLAWS, JR 2,143,690

STEM FOR ELECTRIC LAMPS AND SIMILAR DEVICES Filed Aug, 22, 1936 2 Sheets-Sheet 1 I F F g I. F g. 5. Fig. 7.

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Jan. 10, 1939; J. FLAWS. JR 2,143,690

STEM FOR ELECTRIC LAMPS AND SIMILAR DEVICES Filed Aug. 22, 1956 2 Sheets-Sheet 2 Inventor: John FlawsJn,

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Patented Jan. 10, 1939 UNITED STATES PATENT OFFICE.

John Flaws, Jr., Cleveland Heights, Ohio, assignor to General Electric Company, a corporation.

of New York Application August 22, 1936, Serial No. 97,358

8 Claims.

and similar devices and to methods of manufacturing the same. Stems as generally made at the present time comprise a glass tube through which leading-in wires extend, the inner end of said stem tube being fused and compressed by clamping around portions of said leading-in wires. This results in afiat solid mass of glass, referred to as the stem press, at the inner end of the stem tube. The stem also generally includes a glass exhaust tube which extends through the stem tube, the leading-in wires extending longitudinally between the two tubes. portion of the exhaust tube adjacent to the inner end of the stem tube is fused therewith and forms part of the stem press.

It has been proposed heretofore to make each of the leading-in wires of a single piece of wire and to flatten the portions thereof which are to be sealed in the stem press. However, in order to prevent leakage between the lead wires and the glass, it was found necessary to align the flattened portions of the lead wires parallel to the flattened or long sides of the stem press. This required mechanical positioning of the flat portions of the leads to keep them in place during the fusion and compression of the glass, the said flat portions of the leads being located in a plane passing through the axis of the concentrically disposed stem and exhaust tubes. V Furthermore, due to the small space between the stem and exhaust tubes it was practically impossible to so align the flat portions of the lead wires without distorting them.

One of the objects of the present invention is to provide an improved method of sealing leadingin wires in stems to form an effective gas-tight seal. Another object is to provide a stem construction for flattened leads in which the fiattened portions of the leads are sealed in at right angles to the-flattened or long sides of the press portion of the stem. This construction increases the distance between the lead wires since the flat portions in a stem having two lead wires are parallel to each other instead of being in the same plane, thereby increasing the resistance to electrical leakage and to electrolysis. Further features and advantages of my invention will appear from the following detailed description of species thereof and from the drawings.

In the drawings, Figs. 1, 3, and 7 are side elevations showing various steps in the manufacture of a stem according to my invention; Figs. 2 and 4 are plan views of the stems shown in Figs. 1 and 2 respectively; Figs. 6 and 8 are sections along In this case the My invention relates to stems for electric lamps lines 66 and 88 of Figs. 5 and 7 respectively; Fig. 9 is an enlarged perspective view of one of the flattened leading-in wires; Fig. 10 is a side elevation of stem clamping jaws; Figs, 11 and 12 are perspective views of one pair of stem clamping 5 matrices; and Figs. 13 and 14 are side and plan views respectively of modified apparatus for making the stem.

The method of manufacturing the stem is shown step by step in Figs. 1 to 8 inclusive, and 10 maybe performed on the automatic stem machine disclosed in the United States patent to Fagan and Staudenmeir No. 1,655,141. According to my invention, the stem parts, as shown in Figs. 1 and 2, are first arranged in proper rela- 5 tion to each other, the flared glass stem tube l0 surrounding the exhaust tube I I and the leadingin wires l2 and 13 extending longitudinally therebetween. The leading-in wires l2 and I3, which are preferably made of copper, are round from end to end except for a flattened portion M (Fig.

9) which, in this instance, is reduced to a thickness of about .0015 inch. The copper leading-in wires may be'plated with nickel if desired. In this case the plating is preferably removed from the flattened portions 14. The said flattened portions H of the leading-in wires l2 and I3 are arranged in parallel planes at right angles to the plane passing through the leading-in wires and the axis of the stem tube 10 and exhaust tube The end of the stem tube In is then heated by fires (not shown) which fuse and force the said end of the stem tube around the exhaust tube II and leading-in wires l2 and I3, as shown in Figs. 3 and 4. When the end of the stem tube l0 and that portion of the exhaust tube ll adjacent thereto are in a plastic condition, the mass is pressed together by the matrices l5 and I6 shown in Figs. 5 and 6.. The said matrices I5 40,

and'l6 are fastened to clamping jaws l1 and I8 (Fig. 10) which are attached to pins l9 and 20 pivoting in a stationary block 2| and which are operated from lever 22 through links 23 and 24. The burners are indicated in Fig. 10 at 25 and 26. The matrices l5 and I6 are arranged so as to flatten the end of the stem at right angles to the plane passing through the leading-in wires l2 and I3. The matrices l5 and It; as shown in Figs. 11 and 12, are provided with projections 21 and 28 at the top and bosses 29 and 30 on the faces thereof which form indentations in the stem press. The protuberances 21 and 28 are located above and project out farther than the bosses 29 and 30 and indent the stem press 3| instance the stem 38 is flattened by the matrices in line with the exhaust tube so as to localize the subsequent blow-out of an exhaust aperture through the glass mass, as disclosed in Phelps and Raus Patent 1,659,613. The bosses 29 and 3B squeeze the center portion of the stem press 3| into a thin section in accordance with the disclosure in the Rudd application Serial No. 30,639, filed July 10, I935, and force the glass of the stem press 3| laterally outward so that the section at the flattened portions of the lead wires is I-shaped. The glass is compressed against the adjacent sides of the flattened portions M of the leading-in wires l2 and I3 which in turn are forced against the outer portions of the stem press 3|. Considerable pressure is produced in the stem press 3| since the outer portions thereof are confined between the arms or lugs 32 and 33 on matrix IS. The glass of the stem press 3| is compressed and sealed firmly and securely to the flattened portions l4 of the leading-in wires under these conditions. The excess plastic glass of the stem press 3| is forced downwardly out of the box-like enclosure formed by the matrices I5 and i6.

In order to relieve the strains in the stem press 3| and round out the corners, it is again heated by fires (not shown). The exhaust opening 34 (Fig. 7) is also blown out during the heating and the junction of the inner walls of the stem tube I and exhaust tube adjacent the stem press 3| is rounded by air blown into the stem tube Ill from jet 35. The operations conform to present practice and are supplemented by a second compression of the stem press 3| by matrices 36 and 31 (Fig. 8). These latter matrices 36 and 31 are operated in the same manner as before and may be dispensed with if desired as they alter the shape of the stem press 3| but slightly.

A modified form of apparatus for making the stem press is shown in Figs. I3 and 14. In this 42 and 43 which are attached to the jaws 44 and 45 respectively. The jaws 44 and 45 are attached to pins 46 (only one being shown) which correspond to pins l9 and 20 of the previously described mechanism and which extend through the block 41 mounted on the stationary post 48. The jaws 44 and 45 are each operated as before by a link 49 (only one shown) which is connected to a pin 50 actuated vertically by a lever The saidjaws 44 and 45 reach the closed position when stop screws 52 and 53 engage each other. The matrices 42 and 43 are provided with projections 54 and 55 and bosses 56 and 51 as before and cooperate with slidably mounted matrices 58 and 59 to compress the plastic glass in the slides 60 and 6 I which are apertured for the bolts 62 and 63 respectively and the reduced portions 64 and 65 of the matrices 42 and 43. The slides 60 and 6| are moved so asto bring the matrices 58 and 59 against the stem 38 by the upward movement of the wedge 66 which engages the rollers 61 and 68 on the pins 69 and extending from the slides 60 and 6|. The springs H and 12, which extend between the posts 13 and 14 respectively and the bolt 62 and slide 6| respectively, pull the matrices 53 and 59 away from the stem 38 after it is formed, as the wedge 66 is lowered. Post 14 is mounted on pin 46 and turns therewith. The wedge 66 is mounted on the vertical rod which is slidably mounted in the block 41 and which is moved upward by engagement with the arm 16 extending from pin 50.

The spring 11 located between block 41 and the head 18 of rod 15 returns said rod '15 to its lower position.

The methods and apparatus described above for forming and compressing the stem press around the lead wires may also be employed to advantage when round leads are used instead of flattened leads in order to provide sufficient glass around the lead wires and to properly compress the glass against said wires.

Various changes may be made in the apparatus illustrated. For example, it may be desirable in the matrices shown in Figs. 11 and 12, to provide the matrix I 6 (Fig. 12) with one of the ears or lugs 32 or 33 so that each of the matrices has one of the ears, instead of providing the matrix I5 with both ears 32 and 33.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A stem for an electric lamp or similar device comprising a glass stem tube, a leading-in wire extending longitudinally through said stem tube and having aflattened portion, a portion of said stem tube being fused and flattened and having said flattened portion of said wire embedded therein, the flattened surfaces of said portion of said stem tube being at right angles to the said flattened portion of said leading-in wire.

2. A stem for an electric lamp or similar device comprising a glass stem tube, a pair of leading-in wires extending longitudinally through said stem tube and each having a flattened portion, the said flattened portions of said wires being in parallel planes, a portion of said stern tube being fused and flattened and having said flattened portions of said wires embedded therein, the flattened surfaces of said portion of said stem tube being at right angles to thesaid flattened portions of said leading-in wires.

3. A stem for an electric lamp or similar device comprising a glass stem tube having a portion thereof fused and compressed so as to be approximately I-shaped in transverse cross-section and a pair of leading-in wires extending longitudinally through said stem tube and having flattened portions sealed in the ends of said I- shaped section at right angles to the stem of said I-shaped section.

.4. The method of making stems for electric lamps or similar devices which comprises assembling a glass stem tube and leading-in wires extending longitudinally through said stem tube and having flattened portions, fusing a portion of said stem tube around said flattened portions of said wires, and compressing and flattening said fused portion of said stem tube so that the flattened surfaces thereof are at right angles to the flattened portions of said wires.

5. The method of making stems for electric lamps or similar devices which comprises assembling a glass stem tube and leading-in wires extending longitudinally through said stem tube and having flattened portions, fusing a portion of said stem tube around said flattened portions of' said wires, compressing and flattening said fused portion of said stem tube so that the flattened surfaces thereof are at right angles to the flattened portions of said wires, and indenting the flattened portion of said stem between said wires to squeeze the glass laterally outwardly around and against said wires.

6. The method of making stems for electric lamps or similar devices which comprises assembling a glass stem tube and leading-in wires extending longitudinally through said stem tube and having flattened portions, fusing a portion of said stem. tube around said flattened portions of said wires, compressing and flattening said fused portion of said stem tube 50 that the flattened surfaces thereof are at right angles to the flattened portions of said wires, and indenting the flattened portion of said stem between said wires to squeeze the glass laterally outwardly around and against said wires while confining the said lateral spread by means of a tool to cause the glass to be firmly pressed against both sides of said flattened portions of said wires.

7. The method of making stems for electric lamps or similar devices which comprises assembling a glass stem tube and leading-in wires extending longitudinally through said stem tube and having flattened portions, fusing a portion of said stem tube around said flattened portions of said wires, compressing and flattening said fused portion of said stem tube so that the flattened surfaces thereof are at right angles to the flattened portions 'of said wires, and indenting the flattened portion of said stem between said wires to squeeze the glass laterally outwardly around and against said wires and simultaneously compressing the said flattened portion at the sides to cause the glass to be firmly pressed against both sides of said flattened portions of said wires.

8. The method of making stems for electric lamps or similar devices which comprises assembling a glass stem tube and a pair of leadingin wires extending longitudinally through said stem tube, fusing a portion of said stem tube around portions of said wires, compressing and flattening said fused portion of said stem tube in a direction at right angles to the plane passing through said wires and indenting the flattened portion of said stem between said wires to squeeze the glass laterally outwardly around said wires and simultaneously compressing the said flattened portion at the sides to cause the glass to be firmly pressed around said wires.

JOHN FLAWS, JR. 

